As Ebola threat grows, CDC calls for halt to nonessential travel to West Africa

- Americans are being asked to avoid nonessential travel to the West African nations of Guinea, Liberia and Sierra Leone where history's largest outbreak of the Ebola virus continues to spread throughout the region.

- Americans are being asked to avoid nonessential travel to the West African nations of Guinea, Liberia and Sierra Leone where history's largest outbreak of the Ebola virus continues to spread throughout the region.

The Centers for Disease Control and Prevention on Thursday issued the Level 3 travel warning as outbreaks of the deadly virus occur across all three countries, which share a common border.

"That common border appears to be the epicenter of the outbreaks," said CDC director Tom Frieden in a telephone briefing with reporters.

The CDC will send 50 disease control specialists to the region over the next 30 days to help establish emergency operations centers, strengthen lab networks to speed testing for the disease and build the capacity of local areas to respond to the outbreak, Frieden said.

“This is the biggest and most complex Ebola outbreak in history. Far too many lives have been lost already,” Frieden said. “It will take many months, and it won’t be easy, but Ebola can be stopped. We know what needs to be done."

Frieden said the disease doesn't pose a major threat for the United States because it can only be passed to others by an infected person who's showing symptoms of the disease. Infection can also occur through direct contact with bodily fluids from an infected symptomatic person or direct contact with objects like needles that were contaminated with infected secretions.

The CDC is helping with screening activities in West Africa to prevent sick travelers from getting on planes. The CDC and its partners are not, however, screening passengers traveling from affected countries.